CYANURIC ACID
(A.K.A. STABILIZER OR CONDITIONER)
What is cyanuric acid?
Sunlight can break down active, germ killing, free chlorine in the pool. Cyanuric acid is a chemical that can lessen this effect, but can also make free chlorine less effective.
How does cyanuric acid get into your pool?
Some solid forms of chlorine contain cyanuric acid or it can be added as a supplement. Trichlor and dichlor are two solid forms (tablet, briquette, powder, etc.) of chlorine that are commonly used. Check your disinfectant labels to know if you are using one of these forms of chlorine. Dichlor by weight contains 57% cyanuric acid; trichlor contains 54% cyanuric acid.
Why is cyanuric acid added to your pool?
The amount of free chlorine in the water can last six times longer when it is stabilized with cyanuric acid in the correct concentrations. On a bright sunny day, nearly all of the free chlorine in a pool without cyanuric acid can be lost in less than two hours.
How much cyanuric acid should be used in a swimming pool?
Cyanuric acid is most effective between 30-50ppm.
Should all pools use cyanuric acid?
No, only outdoor pools in direct sunlight that use chlorine as a disinfectant get any benefit from using cyanuric acid. It should not be added to indoor pools or pools that use bromine as a disinfectant.
Does using cyanuric acid in the water affect how I treat the pool water?
Unlike chlorine, cyanuric acid is never used up and builds up in the pool water. Once you have added it to the pool, it will remain in the water. When pools have more than 50ppm of cyanuric acid, it reduces the killing action of chlorine on germs that can make people sick. The best way to reduce cyanuric acid is to partially drain the pool and add fresh water. Some cyanuric acid will cling to the pool surface, plumbing, and filtration system. So even after completely draining and refilling the pool, there will probably be a measurable level of cyanuric acid in the newly added water. Also, do not run your dichlor or trichlor feeder fully open on high and over feed your chlorine. This will over feed your cyanuric acid level as well and you may have to drain some water, and add fresh water. Your chlorine feeder should be used to maintain your chlorine level within the ideal range of 2.0-4.0ppm free chlorine. When you need to shock/superchlorinate your pool, do it appropriately with chlorine that does not contain cyanuric acid and is considered unstabilized (liquid, calcium hypochlorite, etc.). Check the product labels.